Initial route plans (autostrada A3)

The autostrada A3 was a motorway planned from 1993^[4][5] to 2001^[6] that was supposed to be built in western Poland. It was planned to begin in Szczecin, link Zielona Góra, Bolków and end in Lubawka on the Polish-Czech border.

Some road maps published in 1990s had an approximate route of the motorway, which in some places were different from the final route of S3, most notably the motorway was supposed to form north-eastern bypass of Legnica^[7] while S3 was constructed as its western bypass.

In 2001 the decision was made to build a lower standard "express road" as the traffic density was judged too low to justify a motorway.^[8] One legacy of the road having been planned as an autostrada is that from the beginning it was being constructed on a completely new alignment some distance away from the old route of the DK3 road. This is akin to how most expressways in Poland are constructed nowadays, but in contrast to the standards of the 2000s when most of the expressways were being constructed by upgrading existing roads. Like other modern Polish expressways S3, shares the crucial properties of an autostrada, including physical separation, restricted access, all interchanges being grade-separated, and at least two continuous lanes in each direction as well as emergency lanes (hard shoulder).

Świnoujście – Szczecin

One section of S3 east of Szczecin (19 km) was constructed in the 1970s in an expressway standard of those times, featuring one-level intersections and a pedestrian crossing. It was reconstructed in 2019–2020 to contemporary standards, with the intersections and the pedestrian crossing upgraded to grade-separated ones.

S3 south of Szczecin overlaps with A6 motorway (see Autostrada A6: History of construction).

Szczecin – Legnica

A single carriageway was constructed in years 1985–1995 on the section Sulechów–Zielona Góra (27 km). Three short sections were constructed in years 2001–2008, also with the first carriageway only.

The first large section of S3 was the stretch from Szczecin to Gorzów Wielkopolski (82 km), opened to traffic in 2010,^[9] followed by the stretch from Gorzów Wielkopolski to Sulechów (80.6 km), opened to traffic in 2013/2014. The new sections had two carriageways, separated by the older stretches (Sulechów–Nowa Sól, Gorzów Wielkopolski bypass and Międzyrzecz bypass) which still remained as single-carriageway.

In 2014–2017/2018, the expressway between Nowa Sól and Legnica (junction with A4) was constructed, and the second carriageway was added on the three older stretches.^[10] The exception was the section Polkowice - Lubin, which was also contracted to be completed in the first half of 2018, but the deal with Salini Impregilo was terminated in 2019 due to extensive delays in construction. It was ultimately opened to traffic in 2021.

Legnica – border with Czech Republic

Signing the contracts for construction of all four stretches between A4 at Legnica and the Czech border was planned for 2014. However, in 2013 the officials announced that the section will not enter into construction yet, because delays in preparations in the Czech Republic meant that the connecting motorway on the Czech side of the border might enter into construction no earlier than 2018^[11][12] (ultimately, the delays on the Czech side turned out to be even larger and the construction of the connecting stretch is expected to start in 2024 rather than in 2018^[13]). Some of the money allocated for it has been re-purposed to build the S2 expressway in Warsaw.

Later the decision was partially reversed, and in 2014 two tenders were opened for the section between Legnica and Bolków. This part (35.8 km) was constructed in years 2015–2018.^[14]

Two remaining design-build contracts for the section from Bolków to the Czech border were signed in October 2018. The section from Kamienna Góra to the Czech border was opened in September 2023. The other section remains under construction, with expected completion in the first half of 2024.^[15]